1. Technical Field of the Invention
The present invention relates CMP apparatuses, CMP polishing methods, semiconductor devices and methods for manufacturing the same. In particular, the present invention relates to CMP apparatuses that can control cross-contamination even when plural types of polishing processings are conducted with a single apparatus, CMP polishing methods, semiconductor devices and methods for manufacturing the same.
2. Conventional Technology
FIG. 4 schematically shows a cross-sectional view of the structure of a conventional CMP apparatus.
A CMP apparatus 101 includes a turntable 102 in the shape of a disk, and a rotation motor (not shown) is disposed through a rotary shaft below the turntable 102. The turntable 102 is structured such that it normally rotates around its central axis 103. A polishing pad 104 is attached to the upper surface of the turntable 102. The polishing pad 104 includes a lining layer 105, which acts as an interface between a cover layer 106 that is used with a slurry for polishing a wafer 107 and the turntable 102.
A polishing head 108, which is a wafer holding device, is disposed above the turntable 102, and a rotation motor (not shown) is disposed through a rotary shaft 109 above the polishing head 108. The polishing head 108 is structured in a manner that it rotates around its central axis 110. The rotary shaft 109 is supported through an arm 111.
Also, a nozzle (not shown) that discharges a slurry (not shown) onto a central section of the polishing pad 104 is disposed above the turntable 102.
A dresser 112 that prepares the surface condition of the polishing pad 104 is disposed above the turntable 102, and the dresser 112 is mounted on a parallel motion arm 113. The dresser 112 is structured such that it can move in directions indicated by arrows by a moving device (not shown).
When the wafer 107, which is a substrate to be polished, is polished by the CMP apparatus 101, for example, a silicon oxide film is initially deposited on the wafer 107. Then, the back surface of the wafer 107 is attached by a vacuum to the bottom section of the polishing head 108. Then, the turntable 102 is rotated by the rotation motor in a direction indicated by an arrow shown in FIG. 4, and a slurry is discharged from the nozzle such that the slurry is dropped (applied) adjacent the center of the polishing pad 104.
Then, the polishing head 108 is rotated by the rotation motor around the center axis 110, and a surface (polishing surface) of the wafer 107 is pressed against the polishing pad 104. By this, the silicon oxide film on the wafer 107 is polished. Then, the wafer 107 may be polished while the dresser 112 is constantly pressed against the polishing pad 104 to smooth the surface condition thereof. Or, each time the wafer is polished for a predetermined period of polishing time, the dresser 112 may be pressed against the polishing pad 104 to smooth the surface condition thereof.
It is noted that a CMP process is used to planarize a film formed on a substrate to be polished. The target film may be one of a variety of films such as a SiO2 film, Cu film, and W film. The CMP apparatus is mainly composed of a polishing agent called a slurry and polishing cloths called a polishing pad, as described above, in which a wafer that is a substrate to be polished is polished by rotating the wafer and the polishing pad while the slurry is coated on the wafer. Further, there are a plurality of steps in a semiconductor processing which require a CMP apparatus, such as, STI (Shallow Trench Isolation), steps for wiring multiple layers, and the like. However, in order to control cross-contamination among different steps (for example, metal contaminants that are generated in the steps of wiring multiple layers entering in transistor structural sections in the STI step), polishing steps are conventionally conducted by using independent CMP apparatuses for different steps, respectively.
In such a conventional CMP apparatus, independent apparatuses, although the apparatuses have the same hardware structure, need to be used to prevent contamination. The processings with the independent apparatuses may be effective in terms of preventing cross-contamination among different steps. However, they are very inefficient in view of the production, such as, the investment cost for the CMP apparatuses.
In other words, in view of the investment cost, when different CMP apparatuses are installed for different steps, the cost for the apparatuses increases as compared to the case when a plurality of processing steps are conducted by a single CMP apparatus. Also, even when a plurality of CMP apparatuses are installed for different steps, if a substantially large amount of polishing Work needs to be conducted in one of the steps, and if it exceeds the entire processing capacity of the CMP apparatus used in that step, the efficiency of the processing capacity in that particular step reaches the limit, and the production efficiency cannot be improved further. In contrast, when a plurality of processing steps can be performed by each CMP apparatus, and if a large amount of polishing work needs to be conducted in one of the steps, another CMP apparatus that is used in another of the steps can be used. Accordingly, a reduction in the efficiency due to the limit of processing capacity can be prevented, and the rate of production (lead time) can be stabilized by expanding production paths.
The present invention has been made in view of the circumstances described above, and one object is to provide CMP apparatuses that can control cross-contamination even when plural types of polishing processings are conducted with a single apparatus, CMP polishing methods, semiconductor devices and manufacturing methods therefore.